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Math Help - Log/Ex Equation

  1. #1
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    Log/Ex Equation

    I cannot figure out this equation, solving for x.

    4^2x - 4^x - 20 = 0

    Can someone help?

    Thanks,
    Stefan
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by millerst View Post
    I cannot figure out this equation, solving for x.

    4^2x - 4^x - 20 = 0

    Can someone help?

    Thanks,
    Stefan
    note that this is (4^x)^2 - (4^x) - 20 = 0

    let 4^x = y, then you have

    y^2 - y - 20 = 0

    this is just a quadratic equation, hopefully you can solve it for y. when done, replace y with 4^x and solve for x by using the logarihm to the base 4
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  3. #3
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    Thanks, helped a lot.
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